 |
01-10-2025, 11:43 AM
|
#1
|
1 Rivet Member 
2024 25' Flying Cloud
Deland
, Florida
Join Date: Aug 2024
Posts: 8
|
Ducting exhaust from a portable A/C unit
I have a 2024 25' Flying Cloud FBT with a single A/C which I learned is, in Florida, completely inadequate about 5 months of the year. After conferring with the factory about adding a second rooftop unit at an approximate cost of (WOW!) $13,000, I've decided to consider alternatives, one of which to place an auxiliary "portable" A/C between our twin beds and to duct the hot air exhaust through the wall into the front locker and then down through the floor (down by the spare tire). Has anyone done something comparable and is there anything specific to look out for apart from the obvious "don't cut any wires, gas lines or anything else that looks important".
I would bring dedicated power for the unit in on the underside of the locker, and would have the condensation drain tap into the hot air exhaust duct. I'd probably add an exhaust fan inside the exhaust duct to suck the hot air and blow it down since, of course, heat rises, and I'd screen the opening for bugs and rodents.
Thoughts? Pitfalls? Anybody else actually done this?
Tabelmann
|
|
|
01-10-2025, 12:38 PM
|
#2
|
Rivet Master 
1973 21' Globetrotter
Houston
, Texas
Join Date: Sep 2009
Posts: 3,388
|
The biggest pitfall I see with these portable units is that the VAST majority of them have only a hot air exhaust. What you want is one that both draws air in from outside, runs it across the condenser coils, then expels it to the outside. So you need both an intake and an exhaust. Note that these are harder to find, and usually about 30% more expensive than the basic, useless models with only an exhaust.
If you don't have this, then what you are doing is drawing in air from the cabin, cooling it and blowing it back out, but at the same time you are drawing in cooled cabin air, running it across your condenser coil, and exhausting it to the outside. Since nature abhors a vacuum, the air that you just spewed out will be replaced by hot, humid air that gets sucked into the cabin through every crack, door and window seal.
As far as the $13000 quote you got, that seems pretty outrageous. I'd look around for another quote.
Finally, if you are going to go the route of a non-rooftop unit, I would suggest installing a mini-split system, with the condenser unit sitting outside on the tongue. I would think this would be your best combination of efficiency and cost effectiveness.
There are a few threads on these forums about this topic--try searching for "portable AC," and you should get some hits.
good luck!
|
|
|
01-10-2025, 01:08 PM
|
#3
|
Rivet Master 

1966 22' Safari
1955 22' Flying Cloud
Fredericksburg
, Texas
Join Date: May 2015
Posts: 3,114
|
Pioneer now has a 9M and 10M BTU 115V under bench RV heat pump conditioner. A friend of mine in College Station Tx has installed one in his Airstream. He said it works well. We installed and ducted a mini split in our 55 Airstream several years ago that has worked great without issues. Just another option. Good luck
|
|
|
01-10-2025, 03:11 PM
|
#4
|
diesel maniac
Airstream - Other
Tucson
, AZ
Join Date: May 2017
Posts: 2,819
|
Quote:
Originally Posted by Bubba L
Pioneer now has a 9M and 10M BTU 115V under bench RV heat pump conditioner. A friend of mine in College Station Tx has installed one in his Airstream. He said it works well. We installed and ducted a mini split in our 55 Airstream several years ago that has worked great without issues. Just another option. Good luck
|
Those look interesting. From looking at the install instructions am I correct in assuming you need to cut 2 holes in your floor, one for condenser air in and another for condenser exhaust?
I also noted that they don't provide any ducting materials but they sell it separately.
Interestingly the 9K and 10K units are the same dimensions.
__________________
Brian
|
|
|
01-10-2025, 03:21 PM
|
#5
|
Rivet Master 

1966 22' Safari
1955 22' Flying Cloud
Fredericksburg
, Texas
Join Date: May 2015
Posts: 3,114
|
Brian, you do have to cut a couple holes in the floor through the belly pan. Our mini split unit has a 1/2” condensate line. So, it is just a 1/2” hole. We also use a turkey vaster to squirt Clorox through the line to keep it clean. I think the friend of mine that installed one also installed some ducting. Ducting upward helps due to the curvature of the skin.
|
|
|
01-10-2025, 08:46 PM
|
#6
|
Rivet Master 
2023 28' International
Mercer County
, New Jersey
Join Date: Oct 2021
Posts: 792
|
The reason it is so expensive is because it probably also involves upgrading from a 30A to 50A service. No matter what route you take to add the 2nd AC unit, you will probably need to update the service.
Since you have a new trailer, I would see if any dealer may be willing to trade your 24 for a new one with a dual AC unit from the factory.
|
|
|
01-11-2025, 10:44 AM
|
#7
|
Half a Rivet Short
2017 30' Classic
2022 Interstate 24X
Carlisle
, Pennsylvania
Join Date: May 2017
Posts: 16,726
|
Hi
As noted above, the "big deal" is that you can't run two A/C units on a 30A power setup. You need to do *something* about that. Rewiring everything for 50A is expensive, but it's a good way to solve the problem. Going to a second 30A plug is the alternative, that may not work at many campgrounds ....
Bob
|
|
|
01-11-2025, 12:14 PM
|
#8
|
4 Rivet Member 
2017 30' Classic
Bluffton
, South Carolina
Join Date: Jul 2013
Posts: 254
|
The guys at The Dry Campers are installing mini splits. And when they did some repair work to my solar system, (excellent experience by the way) they said they could put them in Airstream’s. These guys do quality workmanship at a fair price.
They travel around the country with their business, but are located in Jacksonville Florida now and are going to be at the Tampa RV super show next weekend.
If that’s something you were interested in, I would check with them.
|
|
|
01-11-2025, 05:21 PM
|
#9
|
Rivet Master 
2019 22' Sport
High River
, Alberta
Join Date: Aug 2006
Posts: 1,356
|
Quote:
Originally Posted by Belegedhel
The biggest pitfall I see with these portable units is that the VAST majority of them have only a hot air exhaust. What you want is one that both draws air in from outside, runs it across the condenser coils, then expels it to the outside. So you need both an intake and an exhaust. Note that these are harder to find, and usually about 30% more expensive than the basic, useless models with only an exhaust.
If you don't have this, then what you are doing is drawing in air from the cabin, cooling it and blowing it back out, but at the same time you are drawing in cooled cabin air, running it across your condenser coil, and exhausting it to the outside. Since nature abhors a vacuum, the air that you just spewed out will be replaced by hot, humid air that gets sucked into the cabin through every crack, door and window seal.
|
Good advice. These end up being very inefficient. In areas with wildfire smoke, they also draw smoke in.
Traditional window air conditioners or mini splits are the way to go.
|
|
|
01-12-2025, 08:41 AM
|
#10
|
Half a Rivet Short
2017 30' Classic
2022 Interstate 24X
Carlisle
, Pennsylvania
Join Date: May 2017
Posts: 16,726
|
Hi
Another random thought:
Having an A/C unit thundering along right next to the bed seems like a tough thing to sleep through. The whole start / stop routine is hard to ignore. Even "down south" in the summer, we turn off the bedroom A/C at night for this reason.
Bob
|
|
|
01-12-2025, 10:53 AM
|
#11
|
Rivet Master 
1973 21' Globetrotter
Houston
, Texas
Join Date: Sep 2009
Posts: 3,388
|
The power consumption issue will be common no matter what you add for a second unit. If the trailer isn't already set up for 50 amp service it would have to be. This doesn't seem like such a big deal to me, but this also lends weight to the idea of a permanently installed unit that would have its own dedicated wiring, as opposed to a portable unit where only a certain outlet would have its dedicated wiring. That brings to mind another issue, which is that most of your outlets are wired for 15A capacity, which again adds weight to the idea of using a permanent unit with dedicated wiring.
What is the cooling capacity of the current roof-top unit?
|
|
|
01-12-2025, 10:58 AM
|
#12
|
4 Rivet Member 
2023 27' Globetrotter
Williamsburg
, Virginia
Join Date: Jan 2014
Posts: 465
|
Quote:
Originally Posted by jeffb831
The reason it is so expensive is because it probably also involves upgrading from a 30A to 50A service. No matter what route you take to add the 2nd AC unit, you will probably need to update the service.
Since you have a new trailer, I would see if any dealer may be willing to trade your 24 for a new one with a dual AC unit from the factory.
|
This is good advice. Your loss on a trade for a similar unit with 50 amp service may be less than $13K, and will be the most elegant solution. The dealer I've bought two Airstreams from now will not sell anything 25' and larger with 30 amp service.
|
|
|
01-12-2025, 07:15 PM
|
#13
|
1 Rivet Member 
2024 25' Flying Cloud
Deland
, Florida
Join Date: Aug 2024
Posts: 8
|
Quote:
Originally Posted by uncle_bob
Hi
As noted above, the "big deal" is that you can't run two A/C units on a 30A power setup. You need to do *something* about that. Rewiring everything for 50A is expensive, but it's a good way to solve the problem. Going to a second 30A plug is the alternative, that may not work at many campgrounds ....
Bob
|
Bob - yeah when I saw the quote I assumed that they had bid for an electrical “do over” to 50 amps, but when I questioned them they confirmed that they had bid on the basis of a separate dedicated circuit (which is what I had specified). Apparently there is just a ton of labor involved in running a drain line and an electrical line from the roof through the wall and out the bottom or side. At any rate, $13K was a killer for me so I’m looking at other alternatives. Thanks for your reply though, you always have great insights and I learn a lot
|
|
|
01-12-2025, 07:18 PM
|
#14
|
1 Rivet Member 
2024 25' Flying Cloud
Deland
, Florida
Join Date: Aug 2024
Posts: 8
|
Quote:
Originally Posted by 69SoulShine
The guys at The Dry Campers are installing mini splits. And when they did some repair work to my solar system, (excellent experience by the way) they said they could put them in Airstream’s. These guys do quality workmanship at a fair price.
They travel around the country with their business, but are located in Jacksonville Florida now and are going to be at the Tampa RV super show next weekend.
If that’s something you were interested in, I would check with them.
|
Thanks for the tip. I’m going to miss the Tampa show but I will try to chase them down and see what they have to say. Jacksonville is just up the road.
|
|
|
01-13-2025, 07:02 AM
|
#15
|
4 Rivet Member 
2017 30' Classic
Bluffton
, South Carolina
Join Date: Jul 2013
Posts: 254
|
Quote:
Originally Posted by Tabelmann
Thanks for the tip. I’m going to miss the Tampa show but I will try to chase them down and see what they have to say. Jacksonville is just up the road.
|
We had some work done by them yesterday. Told Pete about your post. He relayed to me that they’re gonna stop traveling near as much and they’re settling in the Jacksonville area permanently supposedly. he showed me some pictures of an airstream that he had recently added a mini split to. he mentioned that it draws a lot less power than our factory ACs.
After too bad experiences with two different groups in south Florida it was a great experience to have somebody that knew what they were doing to repair our solar lithium upgrades. that was done last January and it has worked flawless ever since.
The Dry Campers #(727) 379-2267
Good luck with your project
|
|
|
01-15-2025, 12:51 PM
|
#16
|
2 Rivet Member 
2016 27' International
Algonquin
, Illinois
Join Date: Apr 2016
Posts: 46
|
I had a second AC installed. Ours is 30 amp. I decided to go with another roof top unit. It has a separate breaker and a separate 30 amp power supply. So if needed I run a 50 amp dog bone split to 2 30 amp outlets off the power post. I don't remember the exact price but it was around $4000. Works great. I did this in Texas for the same reasons.
|
|
|
01-15-2025, 01:07 PM
|
#17
|
3 Rivet Member 
2005 28' Safari S/O
Lakeland
, Florida
Join Date: Feb 2008
Posts: 118
|
Something is wrong?
Quote:
Originally Posted by Tabelmann
Bob - yeah when I saw the quote I assumed that they had bid for an electrical “do over” to 50 amps, but when I questioned them they confirmed that they had bid on the basis of a separate dedicated circuit (which is what I had specified). Apparently there is just a ton of labor involved in running a drain line and an electrical line from the roof through the wall and out the bottom or side. At any rate, $13K was a killer for me so I’m looking at other alternatives. Thanks for your reply though, you always have great insights and I learn a lot
|
I had a second A/C installed in November. Added 30amp plug, drain and a thermostat to new A/C that even had a heat pump. Price installed under $4500. Something is wrong with your quote.
|
|
|
01-16-2025, 12:53 PM
|
#18
|
2 Rivet Member 
2012 25' Flying Cloud
Cuernavaca
, TX
Join Date: Jul 2020
Posts: 23
|
Mini Split is silent!
What I love about our mini split is the absence of noise. It is so quiet. It works better and draws less power.
|
|
|
 |
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
|
|
Thread Tools |
Search this Thread |
|
|
Display Modes |
Linear Mode
|
Posting Rules
|
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts
HTML code is Off
|
|
|
|

Recent Discussions |
|
|
|
|
|
|
|
|
|
|
|